Voltage regulators are ubiquitously used in electronic circuitry and electronic systems and are critical in maintaining the voltage of a power source within acceptable limits; that is, a voltage regulator is necessary to keep voltages within a prescribed range that can be tolerated by the electronic circuitry or system using that voltage. Voltage regulators are used in electronic equipment in which excessive variations in voltage would be detrimental. For example, electronic voltage regulators are found in devices such as computer power supplies where they stabilize the direct current (DC) voltages used by the processor and other circuit components.
There are various categories of voltage regulators, each class having a characteristic circuit architecture and application. Active regulators represent one category of voltage regulators that employ at least one active component, such as a transistor or operational amplifier, and include linear regulators, switching regulators and silicon controlled rectifier (SCR) regulators. Moreover, within these categories, there are often sub-categories of voltage regulator topologies. For example, linear regulators are often classified into series regulators and shunt regulators.
Switching regulators are one common type of voltage regulator. In simple terms, switching regulators rapidly switch a series element on and off, with a duty cycle of the switch controlling how much charge is transferred to a load connected to the regulator. This duty cycle is controlled by a feedback mechanism similar to the feedback scheme used in a linear regulator. Because the series element is either fully conducting or switched off, it dissipates almost no power, thus giving the switching regulator its characteristic high efficiency compared to, for example, linear regulators. One disadvantage of switching regulators, however, is that they require an inductor that acts as an energy storage element, which when integrated on a die, consumes substantial area and requires additional semiconductor process layers.